Yu Jianchun, A Chinese migrant worker from Henan province with no former mathematical training and no college degree, is being hailed as a real-life version of Will Hunting, the character played by Matt Damon in the 1997 Oscar-winning film “Good Will Hunting”, after finding an alternative method to verify Carmichael numbers.

Carmichael numbers, also known as “pseudo primes”, are large numbers that only appear to be prime numbers, which are only divisible by one and themselves. They are used for credit card encryption and online payments, among other things. There are examinations that can be done to find out which numbers are prime and which are Carmichael numbers, but it’s tricky work. Apparently, a young mailman with no studies in advanced mathematics has just come up with a simpler way to verify Carmichael numbers.